This invention is generally in the field of product authentication techniques, and relates to a system for the authentication of products, and a magnetic tag utilized therein.
Forgery of original products is becoming one of the major concerns in the fields of production and distribution, Therefore, considerable efforts have been undertaken throughout the world in the field of protecting the authenticity of goods. The authentication of bottled products, such as alcoholic beverages, perfumes, drugs, is of particular importance for public safety.
Known authentication means are based mostly on the use of optical means, such as special printing and holograms. However, printed authentication tags can easily be counterfeited. As for holograms, their authenticity can be verified only by means of special optical equipment.
Magnetic identification means are also widely used, in particular, in anti-shoplifting systems. Markers made of soft magnetic amorphous alloy ribbons, as disclosed, for example, in U.S. Pat. No. 4,484,184, are the most widely used. The commonly accepted shape of a marker is that of an elongated strip. Although such markers are characterized by their specific response to an interrogating magnetic field, they are not convenient for article authentication, because of the availability of amorphous ribbon in today""s market and possible counterfeit. Another disadvantage of amorphous strip based markers is the fact that the minimum strip width is about 0.5 mm, and therefore it is difficult to conceal the magnetic element of the marker.
U.S. Pat. No. 5,801,630 discloses a method for preparing a magnetic material with a highly specific magnetic signature, namely, with a magnetic hysteresis loop having large Barkhausen discontinuity at low coercivity values. The material is prepared from a negative-magnetostrictive metal alloy by casting an amorphous metal wire, processing the wire to form longitudinal compressive stress in the wire, and annealing the processed wire to relieve some of the longitudinal compressive stress. The disadvantage of using such a material in article authentication applications is associated with the relatively large diameter of a single wire, typically 50 micrometers or more. Another disadvantage is the complicated multi-stage process of the wire preparation. Still another disadvantage of using his material is the brittleness of an amorphous annealed wire (due to the wire annealing), which prevents the use of this material in flexible markers (i.e., to be attached to a flexible item).
Amorphous magnetic glass-coated microwires have been examined and found as characterized by a unique response to an interrogating magnetic field. This is disclosed in the article xe2x80x9cHigh Frequency Properties of Glass-Coated Microwirexe2x80x9d, A. N. Antonenko, E. Sorkine, A. Rubshtein, V. S. Larin and V. Manov, Journal of Applied Physics, Vol. 83, No. 11, 1998, pp. 6587-6589.
It is an object of the present invention to provide a magnetic microwire for use in a magnetic tag for attaching to a product for product authentication purposes, It is another object of the present invention to provide a magnetic tag for use with various kinds of products for product-authentication purposes. The tag is characterized by its unique response to an external alternating magnetic field.
It is still another object of the present invention to provide a hand-held detector device that is capable of unambiguous detection of the magnetic tag.
In accordance with the invention, the magnetic tag (the so-called xe2x80x9cauthentication tagxe2x80x9d) utilizes at least one magnetic element formed of a glass-coated amorphous magnetic microwire characterized by a large Barkhausen discontinuity and a zero or positive magnetostriction. Such a microwire; is therefore characterized by very fast re-magnetization, and, when located in a region of an alternating magnetic field, produces significantly shorter pulses of the field perturbations, as compared to the conventional magnetic elements of the kind specified. If a plurality of the glass-coated amorphous magnetic microwires is used, the microwires are arranged in a spaced-apart parallel relationship extending across the entire tag length or a part of it, The microwires may also be arranged in an encoded spatial pattern like a one-dimensional or two-dimensional bar code.
The glass-coated amorphous magnetic microwire is produced in a one-stage casting process from an alloy having substantially zeroed or positive magnetostriction. In one preferred embodiment of the invention, the alloy is cobalt-based, including more than 60% of cobalt by atomic percentage. For example, Coxe2x80x94Fexe2x80x94Sixe2x80x94B alloy containing 77.5% Co, 4.5% Fe, 12% Si, and 6% B by atomic percentage, or Coxe2x80x94Fexe2x80x94Sixe2x80x94Bxe2x80x94Crxe2x80x94Mo alloy containing 68.6% Co, 4.2% Fe, 12.6% Si, 11% B, 3.52% Cr and 0.08% Mo by atomic percentage, may be used. The microwire made of this Coxe2x80x94Fexe2x80x94Sixe2x80x94Bxe2x80x94Crxe2x80x94Mo alloy shows less sensitivity to external mechanical tensions, due to the fact that in this microwire, the metal core and glass coating are physically attached to each other only in several spatially separated points of contact, rather than being in continuous contact. The construction and method of fabrication of such a microwire piece are disclosed in a co-pending application assigned to the assignee of the present application In another embodiment of the invention, the alloy is Fe-based, for example containing 60% Fe, 15% Co, 15% Si and 10% B.
Generally, the fabrication of the microwire is based on a modified Taylor method, according to which the microwire is cast directly from the melt. It is important that the Taylor process enables metals and alloys to be produced in the form of a microwire in a single operation, thus offering an intrinsically inexpensive method of microwire manufacture.
The hand-held detector according to the invention generates an external AC magnetic field, and identifies the presence of the microwires within the magnetic field region (in the tag) by detecting the unique short re-magnetization pulses produced by the microwires in response to the application of this field.
There is thus provided according to one aspect of the preset invention, a magnetic microwire for use in a magnetic tag attachable to a product, thereby enabling authentication of the product, wherein the magnetic microwire is a glass-coated amorphous magnetic microwire characterized by a large Barkhausen discontinuity and substantially zero or positive magnetostriction, such that the microwire is responsive to an external alternating magnetic field to produce short pulses of magnetic field perturbations.
According to another aspect of the present invention, there is provided a magnetic tag for attaching to a product to enable the authentication of the product, the tag comprising at least one glass-coated amorphous magnetic microwire characterized by a large Barkhausen discontinuity and substantially zero or positive magnetostriction, such that, when the tag is located in a region of an external alternating magnetic field, the at least one microwire is re-magnetized by the magnetic field to produce short pulses of magnetic field perturbations.
It should be noted that the magnetic tag may also comprise the conventional hologram. In this case, the one or more glass-coated amorphous magnetic microwires can be accommodated underneath the hologram.
According to yet another aspect of the present invention, there is provided a detector device for applying to a magnetic tag attached to a product, the tag being composed of at least one glass-coated amorphous magnetic microwire characterized by a large Barkhausen discontinuity and substantially zero or positive magnetostriction, such that said at least one microwire can be re-magnetized by an external alternating magnetic field to produce short pulses of magnetic field perturbations, the detector device comprising:
a magnetic field source operable to generate the alternating magnetic field to cause the re-magnetization of said at least one glass-coated amorphous magnetic microwire, when the microwire is located in a region of said alternating magnetic field; and
a receiver for receiving the short pulses of the magnetic field perturbations and generating a signal indicative thereof.
The case may be such that a product to be protected is a document of the kind provided with an optical bar code or an encoded magnetic strip containing the document-related information. Such a product may, for example, be a ticket, a credit card, a participant card, etc., which provides the document bearer with certain rights, and which is easy to counterfeit. In this case, the product, in addition to the encoded information carrier (optical or magnetic), can be provided with a magnetic tag according to the invention, namely, comprising one or more glass-coated amorphous magnetic microwires. If the information is encoded by means of a bar code (ire., an optical information reader is to be used), the magnetic tag may be placed underneath the bar code. If a magnetic kind of information encoding is considered (magnetic strip), the magnetic tag should be spaced-apart from the magnetic strip.
Consequently, the above detector elements (the magnetic field source and receiver) are used together with the conventional reader of the encoded information (e.g., bar code reader), and are preferably accommodated in a common housing. Preferably, the detector is designed such that the actuation of the encoded information reader is allowed, only if the magnetic tag has been successfully identified. Hence, the authenticity of the product can be determined to ensure that the document bearer receives the prescribed rights.
According to yet another aspect of the present invention, there is provided a product comprising a tag assembly attached thereto, wherein the tag assembly comprises a magnetic tag comprising at least one glass-coated amorphous magnetic microwire characterized by a large Barkhausen discontinuity and substantially zero or positive magnetostriction, such that, when the tag is located in a region of an external alternating magnetic field, the at least one microwire is re-magnetized by the magnetic field to produce short pulses of magnetic field perturbations.
According to yet another aspect of the present invention, there is provided a system for product authentication, the system comprising:
a magnetic tag for attaching to a product, the tag comprising at least one glass-coated amorphous magnetic microwire characterized by a large Barkhausen discontinuity and substantially zero or positive magnetostriction, such that said at least one microwire can be re-magnetized by an alternating magnetic field to produce short pulses of magnetic field perturbations;
a detector device for applying to said tag, the detector device comprising a magnetic field source operable to generate the alternating magnetic field to cause the re-magnetization of said at least one glass-coated amorphous magnetic microwire, when the microwire is located in a region of said alternating magnetic field; a receiver for receiving said short pulses and generating a signal indicative thereof; and
an indicator utility responsive to the signal generated by the receiver to provide an indication signal.